// Copyright (c) 2012 The Chromium Authors. All rights reserved.
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.

#ifndef UI_GFX_SKBITMAP_OPERATIONS_H_
#define UI_GFX_SKBITMAP_OPERATIONS_H_

#include "base/gtest_prod_util.h"
#include "ui/gfx/color_utils.h"
#include "ui/gfx/gfx_export.h"
#include "ui/gfx/shadow_value.h"

namespace gfx {
class Point;
class Size;
}

class SkBitmap;

class GFX_EXPORT SkBitmapOperations {
public:
    // Enum for use in rotating images (must be in 90 degree increments),
    // see: Rotate.
    enum RotationAmount {
        ROTATION_90_CW,
        ROTATION_180_CW,
        ROTATION_270_CW,
    };

    // Create a bitmap that is an inverted image of the passed in image.
    // Each color becomes its inverse in the color wheel. So (255, 15, 0) becomes
    // (0, 240, 255). The alpha value is not inverted.
    static SkBitmap CreateInvertedBitmap(const SkBitmap& image);

    // Create a bitmap that is a blend of two others. The alpha argument
    // specifies the opacity of the second bitmap. The provided bitmaps must
    // use have the kARGB_8888_Config config and be of equal dimensions.
    static SkBitmap CreateBlendedBitmap(const SkBitmap& first,
        const SkBitmap& second,
        double alpha);

    // Create a bitmap that is the original bitmap masked out by the mask defined
    // in the alpha bitmap. The images must use the kARGB_8888_Config config and
    // be of equal dimensions.
    static SkBitmap CreateMaskedBitmap(const SkBitmap& first,
        const SkBitmap& alpha);

    // We create a button background image by compositing the color and image
    // together, then applying the mask. This is a highly specialized composite
    // operation that is the equivalent of drawing a background in |color|,
    // tiling |image| over the top, and then masking the result out with |mask|.
    // The images must use kARGB_8888_Config config.
    static SkBitmap CreateButtonBackground(SkColor color,
        const SkBitmap& image,
        const SkBitmap& mask);

    // Shift a bitmap's HSL values. The shift values are in the range of 0-1,
    // with the option to specify -1 for 'no change'. The shift values are
    // defined as:
    // hsl_shift[0] (hue): The absolute hue value for the image - 0 and 1 map
    //    to 0 and 360 on the hue color wheel (red).
    // hsl_shift[1] (saturation): A saturation shift for the image, with the
    //    following key values:
    //    0 = remove all color.
    //    0.5 = leave unchanged.
    //    1 = fully saturate the image.
    // hsl_shift[2] (lightness): A lightness shift for the image, with the
    //    following key values:
    //    0 = remove all lightness (make all pixels black).
    //    0.5 = leave unchanged.
    //    1 = full lightness (make all pixels white).
    static SkBitmap CreateHSLShiftedBitmap(const SkBitmap& bitmap,
        const color_utils::HSL& hsl_shift);

    // Create a bitmap that is cropped from another bitmap. This is special
    // because it tiles the original bitmap, so your coordinates can extend
    // outside the bounds of the original image.
    static SkBitmap CreateTiledBitmap(const SkBitmap& bitmap,
        int src_x, int src_y,
        int dst_w, int dst_h);

    // Iteratively downsamples by 2 until the bitmap is no smaller than the
    // input size. The normal use of this is to downsample the bitmap "close" to
    // the final size, and then use traditional resampling on the result.
    // Because the bitmap will be closer to the final size, it will be faster,
    // and linear interpolation will generally work well as a second step.
    static SkBitmap DownsampleByTwoUntilSize(const SkBitmap& bitmap,
        int min_w, int min_h);

    // Makes a bitmap half has large in each direction by averaging groups of
    // 4 pixels. This is one step in generating a mipmap.
    static SkBitmap DownsampleByTwo(const SkBitmap& bitmap);

    // Unpremultiplies all pixels in |bitmap|. You almost never want to call
    // this, as |SkBitmap|s are always premultiplied by conversion. Call this
    // only if you will pass the bitmap's data into a system function that
    // doesn't expect premultiplied colors.
    static SkBitmap UnPreMultiply(const SkBitmap& bitmap);

    // Transpose the pixels in |bitmap| by swapping x and y.
    static SkBitmap CreateTransposedBitmap(const SkBitmap& bitmap);

    // Create a bitmap by combining alpha channel of |bitmap| and color |c|.
    // The image must use the kARGB_8888_Config config.
    static SkBitmap CreateColorMask(const SkBitmap& bitmap, SkColor c);

    // Create a bitmap with drop shadow added to |bitmap|. |shadows| defines
    // the shadows to add. The created bitmap would be padded to have enough space
    // for shadows and have original bitmap in the center. The image must use the
    // kARGB_8888_Config config.
    static SkBitmap CreateDropShadow(const SkBitmap& bitmap,
        const gfx::ShadowValues& shadows);

    // Rotates the given source bitmap clockwise by the requested amount.
    static SkBitmap Rotate(const SkBitmap& source, RotationAmount rotation);

private:
    SkBitmapOperations(); // Class for scoping only.

    FRIEND_TEST_ALL_PREFIXES(SkBitmapOperationsTest, DownsampleByTwo);
    FRIEND_TEST_ALL_PREFIXES(SkBitmapOperationsTest, DownsampleByTwoSmall);
};

#endif // UI_GFX_SKBITMAP_OPERATIONS_H_
